Deep venous thrombosis and occult malignancy: an epidemiological study

OBJECTIVE: To determine the risk of subsequent cancer in patients with deep venous thrombosis confirmed by venography. DESIGN: Follow up of all patients who had venography for suspected deep venous thrombosis during 1984-88. Patients were traced through a cancer registry up to 1 January 1991. SUBJECTS: 4399 patients who had phlebography in one hospital. SETTING: General hospital in Malmö, Sweden, serving a population of 230,000. MAIN OUTCOME MEASURE: Number of cancers recorded. RESULTS: 4399 patients had venography for suspected deep venous thrombosis; 604 were known to have a malignancy at the time of venography and were excluded from further analysis. 1383 had deep venous thrombosis, 150 of whom subsequently developed cancer. 182 of the 2412 patients without thrombosis developed cancer. During the first six months after venography 66 patients with thrombosis developed malignancy compared with 37 patients without thrombosis (P < 0.0001). 38 of the cancers in the deep venous thrombosis group were detected by history, physical examination, and laboratory tests. Three patients had postoperative or post-traumatic deep venous thromboses. Only two of the remaining patients would have benefited from early detection by extensive screening. After six months the incidence of cancer was identical in patients with and without thrombosis. CONCLUSION: Deep venous thrombosis is associated with a significantly higher frequency of malignancy during the first six months after diagnosis. Malignancies can be found with simple clinical and diagnostic methods and extensive screening is not required.